The GrowStream™ tubing is comprised of millions of micropores along its entire surface. There are no emitter openings spaced along the tube. The entire tubing interacts with plant root signals that trigger the release of water through its “smart micropores”.
The GrowStream™ system has a smooth interior surface that has been infused with a hydrophilic polymer coating that has a strong chemical bond to water molecules. This chemical affinity binds the water molecules and holds them suspended on the tubing surface. It is the chemical bond that facilitates the transport of water molecules through the intersecting layers of the microporous tubing material, which is composed of durable, non-biodegradable polyethylene or polypropylene. Due to its microporous properties, polyethylene had been used for irrigation tubing back in the 1970s as a forced micro-drip irrigation system. It required higher pressures to force the water out of the tubing material and was not plant responsive. This material was not infused or coated with the hydrophilic polymer that the GrowStream™ system uses and has patented. The description in the initial patent, followed by the extensive studies/trials and RDI’s new patents support the science behind the GrowStream™ technology that prohibits it from “clogging”.
Water-soluble particulates and fertilizers/nutrients will pass through the micropores of the tubing material. Heavy salts and particulate matter do not easily pass through the tiny micropores. Some of these particles will close off larger openings along the tubing’s surface, which actually alters the tubing material’s transitivity properties to increasing retentivity to create a “water-holding reservoir” under low pressure. This allows the tube to contain the water inside the tube at low pressure, preventing it from continuing to drip or release water from the tube (like in a soaker hose or Moist Tube system). These material properties of the tubing are critical to create a closed system reservoir that holds the water under the surface until the plants need it. It is the hydrophilic polymer coating that binds with the water molecules to increase the transitivity of the tubing material. When chemical exudates are released from the plants’ roots, their affinity for water breaks the molecular bond of the water from the hydrophilic polymer and triggers the flow of water from the inside of the tube, through the material and into the surrounding soil for absorption by the roots.
Scientific research and extensive trials over the past decade have demonstrated this phenomenon. In all of the studies, a tube has never become clogged or failed to interact in a plant-responsive irrigation delivery manner. Exposure to sunlight/UV can reduce the plant responsive irrigation properties and deteriorate the GrowStream™ tubing. When amendments are added for delivery through the tubing, they must be water-soluble to pass through the microporous tubing. The flow rate is low and variable along the entire tubing surface, releasing the water through the micropores in areas of the tube that were triggered to release water droplets by plant root signals. The system uses much less water than other delivery systems, so when adding any amendments through the tubing, the water usage should be considered to ensure that all of one amendment has been released throughout the system before another amendment is added that could interact with the first amendment, causing both chemicals to congeal together. Such a chemical interaction could clog the system with this hardened chemical composition.
There is another factor that contributes to clogging of drip emitters, but not RDI’s micropores. RDI is a closed, subsurface system that is filled with water, which is not exposed to air or sunlight. With drip irrigation, a watering event occurs, and then the water is stopped. After the water is shut off to that zone, water droplets are left suspended along the tube and in the emitters. Sunlight, heat, and wind will result in evaporation of the water droplets, leaving behind the particulates that can build up in the tubing and/or emitter openings.
When configuring the GrowStream™ system for irrigation: the type of plant, its root structure, and the expected water usage/needs of the plant must be considered so that the tubing is installed at the appropriate depth and distance from the roots. It is also critical to install the proper number of tubing lines to deliver an adequate volume of water, so that the plant roots have access to the water volume that is needed. Placing the tubing at variable depths and lateral distances is suggested to promote root development and encourage deeper root growth in trees, orchards, and vineyards. With other irrigation systems, water is delivered through scheduled water events.
Water calculations are utilized to determine the amount of water that the plant needs for the time period until the next watering event. Soil percolation and flow rates and emitter spacing are all factored into these water calculations. With this “forced irrigation” method, the system is forcing out a set volume of water over timed intervals, which water the surrounding soil. The plants’ roots cannot absorb all of this water at the flow rate that it is being released, so after the roots have reached their maximum capacity for water absorption, the remaining water is absorbed by the surrounding soil, runs off, and/or percolates into the soil. When the plant needs water again, it will have to pull water from the surrounding soil, until the next watering event. If the water has evaporated or was inadequate to meet the plant’s watering needs until the next
watering event, the roots are going to seek out the water source, growing into emitters and/or strangulating the system, attempting to squeeze out more water.
Plant’s watering needs fluctuate throughout the day and during their growth and development and flowering/producing stages. The GrowStream™ system provides plants access to water whenever they need it, releasing the water through its micropores at a flow rate that matches the roots absorption capacity. The plants can slowly uptake the water that they need, when they need it. This plant responsive delivery method reduces plant stress: improving plant health and reducing pest infestation, diseases and root rot that result from overwatering or underwatering.
The GrowStream™ tubing mimics an underground stream that is always there to provide water to the plants when they need it. GrowStream™ is the plant’s artery or life line for delivering water when it needs it, so plants do not have to grow into the tube or strangulate the tube in search of water. This system is always interacting with plant root exudates and continuously responding to the plant’s root signals. A simple analogy to compare the watering method of typical irrigation systems versus GrowStream™ :
Traditional irrigation system:
When a person is thirsty and requests water to drink – how much water could they drink if they stood with their mouth open and a bucket of water was dumped down their throat? Only a portion could be swallowed and the rest would run off and soak their clothes. The next time that they are thirsty, they could soak the residual moisture from their clothes.
When a person is thirsty and request water to drink – how much more water would they be able to consume be sipping it from a glass? They would certainly be able to drink what they needed in quantities that they can consume to satiate their thirst.
The GrowStream™ tubing has been installed on commercial farms, using heavy machinery for tape-injecting. The tape was buried 6 inches under the soil surface extending in row lengths up to 1200 feet. After the tape was injected and covered over, the water was turned on at 2.0 psi to fill the tubing. The tubes all filled, but depending upon the length of the row, it took between 15-20 minutes to reach the end of the row.
When the Growstream tubing is inflated, it is not inflated with a high pressure, so the tube has “give” or flexibility to it. Compare this to a water balloon that is filled with a small amount of water. It takes a great deal of force and impact to burst the balloon. However, if a balloon is inflated with a large volume of water, just dropping it on the ground will cause it to burst.
Monitoring the pressure is the best method to identify a leak in an area. Although RDI does not require different zones to cycle water events to provide for adequate water pressure and to meet different watering requirements of plants in a zone, we do recommend separating large areas/projects into sections, so that any damage or punctures that occur can be more readily identified. In each section, a pressure gauge is installed on the pressure regulator at the head of the area, and then a pressure gauge is installed at the end of the area. No pressure or a significant drop in pressure from the head pressure to the end pressure of the system can be used to detect a problem. If the pressure drops, that section can be walked to identify the damaged area. If the tube was punctured, the system is close to the surface and is receiving water continuously at a low pressure. Although a puncture to the GrowStream™ tube won’t cause a geyser or a fountain, like with drip or spray heads, it will leak water and cause a moist/damp area on the surface. This can be located in the section where a pressure drop was noticed.
Another system management component that is recommended for large projects, like a golf course, parks or landscaped areas long roadways, is in-line water metering of sections/zones. The GrowStream™ system configuration for these projects recommends including a battery-operated water meter that uploads the data to the internet, which allows remote monitoring and reports for the various zones/sections of the course/project. This system will also send alerts to a mobile number based upon programmed parameters, such as a 30% increase in water usage for that area over the past 24 hours (area needs to be checked for potential leak) or drop in water usage (has water supply been decreased or shut-off).
When initially installed, the GrowStream™ tube will release water for about 5-14 days (the cure period). The time varies based upon the water quality and the system pressure. The higher the particulate count of the water, the faster the system will stop releasing water and then just hold the water until triggered by root exudates. Running the system at a lower pressure will delay the time for the tubing to cure. This “curing process”, when the system is leaking water provides time for seeds to germinate and/or good soil moisture to reduce plant shock for seedlings and new sod/transplants.
Tubes need to be near the roots of the plants or trees that need irrigated. Many plants and trees send a tap root and/or roots deeper into the soil in search of moisture in the deeper layers that has percolated down from rain. Plants also have roots that are more superficial and extend laterally and at different levels in the surrounding soil. Consider the plant’s root network like a neural network that sends out signals. The aspen tree is a good example of plants’ complex root structures. A group of aspen trees is considered a singular organism with the main life force underground in an extensive root system. When a fruit tree is stressed for water, its root system will send out the signals that interact with our tubing to release water. If the superficial roots received water from the tube, but the tree still needs more water so the roots in the deeper layers continue seeking water; the trees network will continue releasing signals that interact with GrowStream’s™ tube to continue releasing water. The superficial roots will intake water at their absorption rate, but excess water will percolate down through the soil to deliver water to the deeper roots, if the tree is still in need of water.
The roots do not need to touch the tube. They can emit signals from 6-8 inches (15-20cm) away. In the root biopsies that have been performed on various plant tests, superficial roots grew along the tubing, forming a “root sock”. Deeper tap roots were still seen, but the fibrous, more superficial root network surrounded the tubing, forming a synergetic relationship to trigger the release of water into the surrounding soil when needed by the plants’ network.
The current GrowStream™ product is better suited for long-term use in lawn/landscape and permanent crops, like citrus trees, grapes, almonds, date trees, etc. It is also well suited for use with crops that have multiple harvests/seasons, like alfalfa and other forage grasses, sugar cane, artichokes, etc. GrowStream™ can be used for seasonal crops. The tubing can be left in the ground after the final harvest of a seasonal crop. After the crop is harvested and the plant stacks are cut (not pulled from soil), the water supply should be left on for a minimum of a few days (3-5 days). Cutting plants causes stress, so the roots emit signals for water. The GrowStream™ system should remain turned on, so that it can release water in response to this immediate “stress reaction” from the roots. If the system is shut off immediately after the plant stalks are cut, the residual roots could strangulate the GrowStream™ tube trying to obtain water from it. After a few days, the water supply to Growstream should be turned off and the roots are left to die. The field must be left dormant and allow for the roots to dry and decompose. The field can be replanted then, if no till or surface till practices are used.
It is very difficult to pull out the Growstream tubing after a seasonal crop. Since the tubing is 4-6 inches below the surface and has had roots growing all along and around its surface (the root sock). After the roots have died, dried, and decomposed partially, then the tube can be pulled from the ground, but the excessive force to extract the tubing may damage the tube and result in leaks when reused for the next planting. RDI is currently working on manufacturing a less expensive, less durable material for a single-use irrigation tubing, but this would not be warrantied for long-term installations. This product will not be available for at least a year or more.
Once the system has been installed and has been filled with water, the water supply can be turned off and the water in the tubing will gradually be released from the system as drawn out by the plants. It is not recommended to shut off the water, if plants are not dormant and still need water from the system.
If the system is used in an area that experiences Winter with cold temperatures and ground freezes, then the water supply can be turned off during the Fall season before ground freezes. The system can be turned on/recharged in the Spring, after the danger of freeze has passed. It is recommend that when the tubing is initially installed that it is filled with a low pressure, starting at .5 psi. The water slowly travels through the system, gradually expanding the tube through the path of least resistance. As the tube begins partially filling throughout its length, the pressure can gradually be increased up to 1 psi, then1.5 psi, then 2 psi.
A 50 to 100 micron filter is recommended, depending upon the water quality and the client’s concern for greater filtration. Brackish water can be used with Growstream. Regular tubing flushes should be scheduled to flush any build-up of salts in the system. The frequency of the system flushing, depends upon ppm and the salinity, Brackish water should not diminish the life of the tube, as long as, periodic flushes of the tubing throughout the system are performed.